There was a major fibre optics cut east of Russelville, Arkansas. The resident Nuclear Regulatory Commission person notified Emergency Planning that their contact with Arlington and headquarters was out, including commercial lines. Subsequent investigations revealed that ERCS, END and Health Physics Network lines were not functioning at Arkansas Nuclear One. The fibre optic cut was repaired and all phone circuits were operable by 1618 CST April 6, 2005. (#1)